Sculptor Rocky" Thorne (Richard Dix) is branded a coward by his fiance Nancy Adams (Elizabeth Allan) as the United States enters World War 1. Rocky enlists into service and trains as an aviator to prove his worth to Nancy. Wounded during his first aerial engagement, Rockys attitude towards the war changes and the heat of battle turns him into a cold-blooded killing machine. With the instability in Europe foreshadowing the beginnings of World War 11, Ace of Aces is timely as it tackles the horrors of war and how it transforms the participants. As Rocky abandons his principles and embraces the darkness, Nancy discovers the high price paid by the young men and women involved. The film also stars Ralph Bellamy, Theodore Newton and, in an uncredited role, the first of a handful of acting roles, William Cagney (younger brother of James).